[unreadable] One and a half Americans are brain injured each year. Of those, approximately 50,000 of the people will die and 80,000 will suffer long-term disabilities. The proposed research will use an animal model of closed head injury to study whether enriched environments affect recovery. The project includes two experiments and 240 male and female Sprague-Dawley rats. The proposed work will compare effects of no enrichment, social enrichment, physical enrichment, combined social and physical enrichment on behavioral responses in neurologically-intact and brain-injured rats. Experiment 1 is a 2 (no social enrichment or social enrichment) x 2 (no enrichment or physical enriched environment) x 2 (male or female) in neurologically-intact animals. Experiment 2 follows the same experimental design but will study animals that have been brain injured using a fluid percussion device to model closed head injury. The behavioral dependent variables are locomotor activity, acoustic startle reflex responses and pre-pulse inhibition of acoustic startle responses, and performance in the Morris water maze. The proposed work is designed to determine the extent to the specific contributions of social or physical enrichment enhance recovery from head injury and whether there are gender differences in these effects. The long-term goal of this project is to improve treatment programs for rehabilitation and recovery from head injuries. [unreadable] [unreadable]